{PDOC00511}
{PS60032; GH9_1}
{PS00592; GH9_2}
{PS00698; GH9_3}
{BEGIN}
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* Glycosyl hydrolases family 9 (GH9) active sites signatures *
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The microbial degradation of cellulose and xylans requires several types of
enzymes such as endoglucanases (EC 3.2.1.4), cellobiohydrolases (EC 3.2.1.91)
(exoglucanases), or xylanases (EC 3.2.1.8) [1,2]. Fungi and bacteria produces
a spectrum of cellulolytic enzymes (cellulases) and xylanases which, on the
basis of sequence similarities, can be classified into families. One of these
families is known as the cellulase family E [3] or as the glycosyl hydrolases
family 9 [4,E1]. The enzymes which are currently known to belong to this
family are widely distributed among bacteria, fungi, amoebozoa, invertebrate
metazoans, mosses, ferns, gymnosperms, and angiosperms:
- Butyrivibrio fibrisolvens cellodextrinase 1 (ced1).
- Cellulomonas fimi endoglucanases B (cenB) and C (cenC).
- Clostridium cellulolyticum endoglucanase G (celCCG).
- Clostridium cellulovorans endoglucanase C (engC).
- Clostridium stercoararium endoglucanase Z (avicelase I) (celZ).
- Clostridium thermocellum endoglucanases D (celD), F (celF) and I (celI).
- Fibrobacter succinogenes endoglucanase A (endA).
- Pseudomonas fluorescens endoglucanase A (celA).
- Streptomyces reticuli endoglucanase 1 (cel1).
- Thermomonospora fusca endoglucanase E-4 (celD).
- Dictyostelium discoideum spore germination specific endoglucanase 270-6.
This slime mold enzyme may digest the spore cell wall during germination,
to release the enclosed amoeba.
- Endoglucanases from unicellular green microalgae, such as the unicellular
alga Chlamydomonas reinhardtii or the colonial algae Gonium pectorale and
Volvox carteri. Microalgae can utilize cellulose for growth in the absence/
limitation of other C-sources by secreting endocellulases.
- Endoglucanases from plants such as Avocado or French bean. In plants this
enzyme may be involved in the fruit ripening process.
- Invertebrate endoglucanases, secreted by salivary glands and the gut.
Three conserved regions in these enzymes are centered on conserved residues
which have been shown [5,6,7] to be important for the catalytic activity. The
first region contains the characteristic DAGD motif, where the C-terminal D
acts as the catalytic base that extracts a proton from the nucleophilic water.
The second region contains an active site histidine and the third one contains
two catalytically important residues: an aspartate and a glutamate. The fully
conserved nucleophilic D forms H-bonds with the residues of the active-site
loop, comprising of regions I and II, to bring it in the proper alignement.
The fully conserved E acts as an acid that protonates the leaving group and
stabilizes the positively-charged oxocarbonium transition-state. We have used
these three regions as signature patterns, with the first pattern
corresponding to region I, the second to region II and the third to region
III.
-Consensus pattern: [LVS]-x-[GK]-G-[WFYLM]-[YHF]-D-[ACGS]-G-[DSN]-x(2)-[KMR]-
[FAILY]-x-[FWYLQTV]-[APTNS]-[MLGAQS]
[The C-terminal D is an active site residue]
-Sequences known to belong to this class detected by the pattern: ALL, except
two partial sequences.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Consensus pattern: [HLY]-[AILMV]-[FIL]-G-x-[NSTW]-x(2,4)-[SCTV]-[FY]-
[LIVMFY]-[SITV]-G-x(1,5)-[GSY]-x(2)-[AFPSTY]-[FLPSV]-x(2)-
[AILPQVM]-[HV]-[DHLS]-[KRS]
[H is an active site residue]
-Sequences known to belong to this class detected by the pattern: ALL.
one partial sequence.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Consensus pattern: [FYW]-x-D-x(4)-[FYW]-x(3)-E-x-[STA]-x(3)-N-[STA]
[D and E are active site residues]
-Sequences known to belong to this class detected by the pattern: ALL, except
for Fibrobacter succinogenes endA whose sequence seems to be incorrect.
-Other sequence(s) detected in Swiss-Prot: 2.
-Expert(s) to contact by email:
Siddiqui K.S.; ksiddiqui@kfupm.edu.sa
Henrissat B.; bernie@afmb.cnrs-mrs.fr
-Last update: November 2018 / Text and old pattern revised; new pattern added.
[ 1] Beguin P.
"Molecular biology of cellulose degradation."
Annu. Rev. Microbiol. 44:219-248(1990).
PubMed=2252383; DOI=10.1146/annurev.mi.44.100190.001251
[ 2] Gilkes N.R., Henrissat B., Kilburn D.G., Miller R.C. Jr., Warren R.A.J.
"Domains in microbial beta-1, 4-glycanases: sequence conservation,
function, and enzyme families."
Microbiol. Rev. 55:303-315(1991).
PubMed=1886523
[ 3] Henrissat B., Claeyssens M., Tomme P., Lemesle L., Mornon J.-P.
"Cellulase families revealed by hydrophobic cluster analysis."
Gene 81:83-95(1989).
PubMed=2806912
[ 4] Henrissat B.
"A classification of glycosyl hydrolases based on amino acid sequence
similarities."
Biochem. J. 280:309-316(1991).
PubMed=1747104
[ 5] Tomme P., Chauvaux S., Beguin P., Millet J., Aubert J.-P., Claeyssens M.
"Identification of a histidyl residue in the active center of
endoglucanase D from Clostridium thermocellum."
J. Biol. Chem. 266:10313-10318(1991).
PubMed=2037583
[ 6] Tomme P., van Beeumen J., Claeyssens M.
"Modification of catalytically important carboxy residues in
endoglucanase D from Clostridium thermocellum."
Biochem. J. 285:319-324(1992).
PubMed=1637316
[ 7] Guerriero G., Sergeant K., Legay S., Hausman J.-F., Cauchie H.-M.,
Ahmad I., Siddiqui K.S.
"Novel Insights from Comparative In Silico Analysis of Green
Microalgal Cellulases."
Int. J. Mol. Sci. 19:0-0(2018).
PubMed=29914107; DOI=10.3390/ijms19061782
[E1] https://www.uniprot.org/docs/glycosid
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